Zoology - Principles of Inheritance and Variation Question with Solution | TestHub

Phenylketonuria:

Cause: This inborn error of metabolism is also inherited as the autosomal recessive trait. The affected individual lacks a liver enzyme called phenylalanine hydroxylase that converts the amino acid phenylalanine into tyrosine. The genes for the disease are located on chromosome no. 12.

Symptoms: Since phenylalanine is not converted, phenylalanine is accumulated and converted into phenylpyruvic acid (keto derivative) and other derivatives. Accumulation of these in the brain results in mental retardation. These are also excreted through urine because of its poor absorption by the kidney.

Treatment: Diet rich in tyrosine and lacking phenylalanine.